Trailer back-up brake release for surge operated brakes

ABSTRACT

A surge brake actuator which includes two relatively movable members, one connected to a towing vehicle and the other connected to a trailer, is held in an extended position by spring means which is collapsible upon relative movement between the vehicle and trailer. Trailer brake applying means, including a hydraulic brake master cylinder, is operatively connected to one of said members to respond to relative movment between said members for applying the trailer brakes. A mechanism responsive to a backing maneuver of the vehicle and trailer is operatively connected to said brake applying means for rendering said brake applying means ineffective to apply said trailer brakes.

United States Patet Gatt TRAILER BACK-UP BRAKE RELEASE FOR SURGEOPERATED BRAKES Michael Earl Gait, South Bend, 1nd.

The Bendix Corporation, South Bend, Ind.

Filed: Feb. 24, 1972 Appl. No.: 228,936

Inventor:

Assignee:

US. Cl. 188/112 Int. Cl B60t 7/20 Field of Search 188/112; 180/103References Cited UNITED STATES PATENTS l/l960 Smith l/l961 Parkhurst11/1966 Wilson 188/112 Aug. 28, 1973 Primary Examiner-Duane A. RegerAttorney-Ken C. Decker et a1.

[57] ABSTRACT A surge brake actuator which includes two relativelymovable members, one connected to a towing vehicle and the otherconnected to a trailer, is held in an extended position by spring meanswhich is collapsible upon relative movement between the vehicle andtrailer. Trailer brake applying means, including a hydraulic brakemaster cylinder, is operatively connected to one of said members torespond to relative movment between said members for applying thetrailer brakes. A mechanism responsive to a backing maneuver of thevehicle and trailer is operatively connected to said.

brake applying means for rendering said brake applying means ineffectiveto apply said trailer brakes.

1 Claim, 4 Drawing Figures Patented Aug. 28, 1973 2 Sheets-Sheet 1Patented Aug. 28, 1973 3,754,623

2 Sheets-Sheet 2 TRAILER BACK-UP BRAKE RELEASE FOR SURGE OPERATED BRAKESBACKGROUND OF THE INVENTION This invention relates to surge brakeactuators for applying the brakes of a trailer when it tends to overrunor push the vehicle towing it.

It is an accepted fact that house trailers, recreational trailers, andsmall cargo carrying trailers which are drawn by automobiles present acontrol problem when braking even under the best of conditions. Thisproblem is compounded as the speed of the vehicle and the weight of thetrailer increases. Various types of braking systems have been employedon trailers, including pneumatic, electric, and surge braking. Of thesesystems, pneumatic and electric brake actuation of the trailer is oftendone by the vehicle driver separately and independently of the vehiclebraking and unless the driver is skilled it can be extremely hazardousin heavy traffic and on curves, especially if braking between thevehicle and trailer is not coordinated.

It is the surge brake actuator with which we are presently concerned.This actuator is incorporated into the coupling connection or hitchbetween a towing vehicle and a trailer to apply the trailer brakesautomatically if the trailer tends to overrun or push the vehicle. Inspite of the popularity of the surge brake actuator and its wideacceptance on trailers towed by automobiles, the surge actuator has onesignificant disadvantage. That disadvantage is the inexpedientapplication of the brakes on the trailer during a backing maneuverresulting from the trailer tending to overrun the automobile to which itis hitched. Braking the trailer during a backing maneuver is, of course,very undesirable since it interferes with guiding and maneuvering thetrailer. This trailer backing problem could be resolved if the trailerwheels were free to roll. It is to be noted that a less effective brakemust be installed on trailersusing present day surge actuators in orderto back the trailer with a minimum of resistance to back-ing. Using aless effective brake on the trailer is not the answer since thatapproach only magnifies the hazards of trailer braking.-

SUMMARY OF THE INVENTION A principal object of the invention is theprovision of an improved surge brake actuator adapted to be located inthe hitch connection between a towing vehicle and a trailer forwithholding application of the trailer brakes when the vehicle andtrailer are being backed.

Another object of the invention is the provision of a surge brakeactuator incorporated in the hitch between a towing vehicle and atrailer for automatically applying the trailer brakes when the trailertends to overrun the vehicle while moving forward but ineffective inapplying the trailer brakes when the trailer and vehicle are beingbacked.

A still further object of the invention resides in the provision of asurge brake actuator having two resiliently opposed relatively movablemembers connected respectively to a towing vehicle and to a trailer andhaving trailer brake applying means including a force transmittinglinkage and a master cylinder operative upon relative movement betweensaid members for applying said trailer brakes, and wherein the brakeapplying means is rendered impotent by a mechanism responsive to thetowing vehicle being backed.

Still another object of the invention is to provide a spring loadedsurge brake actuator for connecting a towing vehicle to a trailer whichincludes trailer brake applying means operative upon collapse of thespring loaded actuator when the trailer tends to overrun the vehicle,and wherein a mechanism responsive to a backing maneuver of the towingvehicle is mechanically connected with said brake applying means toforestall the collapse of said actuator so that the trailer brakes arenot applied.

A more specific object of the invention is to provide a surge brakeactuator having two resiliently opposed relatively movable membersconnected respectively to a towing vehicle and to a trailer and havingtrailer brake applying means including a force transmitting linkage anda master cylinder operative upon relative movement between said membersfor applying said trailer brakes, and wherein valve means responsive tothe towing vehicle being backed is operatively connected to the outletof the master cylinder so that said brake applying means is ineffectiveto apply the trailer brakes.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a view in perspective of thepreferred embodiment of the invention shown associated with one type ofsurge brake actuator;

FIG. 2 is a view in cross section taken along the line 22 of FIG. 1;

FIG. 3 is a fragmentary sectional portion of the left end only of FIG.1, showing a modified form of the surge brake actuator; and

FIG. 4 is a partial sectional view showing diagrammatically a modifiedform of the invention.

DETAILED DESCRIPTION Referring now to FIG. 1 of the drawing, there isshown a trailer brake actuator 10 having two relatively movable members12 and 14 which are adapted to be secured respectively to a trailer anda towing vehicle. The member 12 is mounted to the trailer structure 16and the member 14 is pivotally connected to the towing vehicle structure18 through a hitch 20 of standard construction, commonly termed a balland socket joint. The members 12 and 14 are of tubular construction andare coaxially arranged one within the other. They are yieldably andcollapsibly retained in an extended position by spring means 22including a coil spring 24 preloaded or caged between the members 12 and14. One end of the coil spring 24 abuts a radially inwardly extendingflange 26 formed at the upper end of the member 14. The other end of thespring 24 engages a retainer element 28 mounted to a transverse pin 30having outer ends 32 which pass through longitudinally extending slots34 in the diametrical sides of the tubular member 12, as best shown inFIG.'2. The ends 32 of the pin 30 are carried in arms 36 of a lever 38.The lever 38 is pivoted at 40 in a bracket 42 attached to the bottomside of the member 12. The top end of the lever 38 is formed with anupwardly projecting flared end portion or lip 46 formed in lever 47which is pivotally mounted by pins 48 to the member 12 so as tolockingly retain the lever 38 in the position shown in FIG. 1. A cable50 has one end secured to the top side of the lever 47 and its other endconnected to the towing vehicle for a purpose fully explained incopending U. S. application Ser. No. 47,069, now U.S. Pat. No.3,647,032, filed June 17, 1970 and assigned to the common assignee ofthe present invention. In the latched position of the levers 38 and 47,as shown in FIG. 1, the spring 24 holds the members 12 and 14 inextended position so that resilient spacer 52 is compressed between theflange 26 of the member 14 and a radially inwardly extending flange 54at the outer end of the member 12. These flanges or abutments 26 and 54restrict the extended position of the two members 12 and 14.

Trailer brake applying means 56 is operatively connected to the tubularmember 14 by a stud or bolt 58 located transversely of the member 14 andto a conventional automotive master cylinder 60 having an outlet port 62in communication with trailer brakes 64. The brake applying meansincludes a force transmitting linkage having a conventional shockabsorber 66, a rod member 68 having a slot 70 therein through which thepin 30 passes, and a master cylinder push rod 72 which threadedlyengages small diameter portion 74 of the member 68. The master cylinder60 is mounted to an end plate 76 which is fastened to a flange portion78 of the tubular member 12 by bolts 80. Details of the construction andoperation of the surge brake control are more completely described incopending U. S. application Ser. No. 47,069, filed June 17, 1970, ownedby the common assignee of the present invention and in cororated hereinby reference.

A mechanism 82, operative upon a backing maneuver of the towing vehicleand trailer for rendering said brake applying means ineffective to applythe trailer brakes, is mounted on the tubular member 12 by a bracket 84.The mechanism 82 includes an electrically operated solenoid device 86havinga bifurcated armature 88 with depending legs 90 and 92 forstraddling the rod member 68 of the force transmitting linkage. The legs90 and 92 are guided in openings 94 and 96 respectively in the bottomwall of the tubular member 12. The upper end of the armature 88 passesthrough an opening 98 of the member 12. When the solenoid device 86 isde-energized, which is the position shown in FIG. 1, a spring 100 urgesthe armature upwardly so that the rod member 68 will slide to the leftbetween the legs 90 and 92. Upon energization of the device 86, thearmature 88 shifts downwardly into engagement with and overlying thesmall diameter portion 74 to thereby provide locking means for the brakeapplying means 56. In the energized position of the armature, anabutment 102 formed at the junction between the small diameter portion74 and the rod member 68 is in locking engagement with the armature 88,preventing the force transmitting linkage from driving master cylinderpiston 104 into bore 106 to apply the trailer brakes 64. A wire 108 ofthe device 86 is adapted to be connected to the towing vehicleselectrical circuit which includes its backup lights so that any backingmaneuver of the vehicle and trailer immediately actuates the mechanism82 causing the armature 88 to shift into the path of movement of theabutment 102 to thereby render said trailer brake applying meansineffective. The locking position of the armature 88 on the abutment 102is best shown in dotted lines in FIG. 2. It is to be observed that thewire 108 may alternatively be connected to the towing vehicleselectrical system in a manner to cause the armature 88 to respond toreverse gear selection on the vehicle, thus energizing said device 86during a backing maneuver so that the trailer brakes are unapplied.

In FIG. 3 the hydraulic master cylinder has been eliminated and thebrake applying means is drivably connected to lever means 120 having abracket 122 supported in the end plate 76 of the tubular member 12. Alever arm 124 is rotatably mounted to the bracket 122 by a pin 126secured to the upper end portion of the bracket. The arm 124 is adaptedto be connected to mechanical type trailer brakes, as distinguished fromhydraulic brakes, through a cable 128. Substituting the lever means 120for the master cylinder 60 permits using the surge brake actuator ofFIG. 1 with mechanical trailer brakes.

MODE OF OPERATION In a situation when both the towing vehicle and thetrailer are moving forwardly at a fairly constant speed along thehighway, the relative positions of the component parts of the surgebrake actuator will be as shown in FIG. 1. At this time the members 12and 14 are in their extended positions. Should the towing vehiclesoperator apply the brakes on the towing vehicle, causing it todecelerate, initially the trailer will tend to continue moving at aconstant speed, so that relative movement will occur between the members12 and 14, collapsing the spring 24. Since the brake applying means 56is connected to the member 14 at one end and to the member 12 at itsother end, relative movement between these members causes the mastercylinder piston 104 to move down the bore 106 to thereby developpressure at the outlet port 62 to apply the trailer brakes 64 in amanner well known in the brake art. As soon as the vehicle and trailerare again moving forwardly at relatively constant speeds with respect toeach other, the piston 104 will have been returned to the position shownin FIG. 1, thus releasing the trailer brakes and locating the members 12and 14 in their extended position.

Should a backing maneuver of the towing vehicle and trailer be desired,the towing vehicles reverse gear is selected which connects the backinglight. circuit of the vehicle with the solenoid 86 of the mechanism 82.This energizes the solenoid 86 causing the armature 88 to shiftdownwardly into the path of movement of the abutment 102, therebylocking the brake applying means 56 including the force transmittinglinkage against displacing the master cylinder piston 104 of FIG. 1 0rrotating the lever 124 in FIG. 3 when the vehicle is backed. In each ofthe situations of FIGS. 1 and 3, the trailer brake applying means isrendered ineffective to apply the trailer brakes when backing.

DESCRIPTION OF ALTERNATE EMBODIMENT Those parts in the alternateembodiment which are the same as those in the preferred embodiment willuse the same reference numeral. In the alternate embodiment of FIG. 4,there is shown the master cylinder 60 of FIG. 1 operatively associatedwith a surge brake actuator which can be considered identical to that ofFIG. 1, except that the mechanism 82 is omitted. Such a surge actuator,omitting the mechanism 82, is shown in U. S. application Ser. No.47,069, filed June I7, 1970 and incorporated herein by reference.

With reference to FIG. 4, a mechanism 200 secured to trailer structure202 is associated with brake apply ing means 56 in such a manner as torender said brake applying means ineffective to apply the trailer brakes204 during a backing maneuver. The mechanism 200 is located at theoutlet 62 of the master cylinder and includes valve means 206 positionedin hydraulic line 208 connecting the outlet port 62 with the trailerbrakes 204. The valve means 206 is provided with a valve member 210normally urged off its seat 212 by a spring 214. The valve member 210 isslidably carried in solenoid device 216 for engagement with the seat 212upon energization of the device by connecting it to the backup lightcircuit of the towing vehicle or alternatively adapting the device to beenergized upon selection of reverse gear in the towing vehicle.

During forward movement of the vehicle and trailer the surge actuatorfunctions the same as in FIG. 1. However, during a backing maneuver ofthe vehicle and trailer the solenoid 216 of the mechanism 200 isenergized due to reverse gear selection of the towing vehicle. Thisforces the valve member 210 onto the seat 212 interrupting the flow offluid from the outlet port 62 to the brakes 204. This action of thevalve member 210 functions to render the brake applying meansineffective to operate the trailer brakes.

I claim:

1. In a trailer brake actuator:

a pair of relatively movable members, one of said members being adaptedto be connected to a towing vehicle and the other of said members beingadapted to be connected to a trailer having brakes;

trailer brake-applying means carried by the other member;

linkage means interconnecting said one member with the trailerbrake-applying means and responsive to relative movement between saidmembers to move in a brake-applying direction to actuate said trailerbrake-applying means to thereby actuate the trailer brakes;

said other member having a tubular section, said linkage means extendinginto said tubular section and having a transversely extending abutmentsurface within said tubular section; and

locking means carried on said tubular section, said locking meansincluding a plunger having a bifurcated end presenting a pair of legs,said legs straddling said linkage means, said tubular section having apair of openings receiving said legs and a third opening opposite said'pair of openings receiving the opposite end of said plunger, andelectrically actuated means adapted to be connected to the vehicleback-up light circuit and being actuatable to shift said plunger from afirst position permitting said linkage means to move relative to thetubular section to a second position in which the plunger cooperateswith the abutment surface to inhibit movement of the linkage means,thereby inhibiting operation of the trailer brake-applying means toprevent actuation of the trailer brakes.

1. In a trailer brake actuator: a pair of relatively movable members,one of said members being adapted to be connected to a towing vehicleand the other of said members being adapted to be connected to a trailerhaving brakes; trailer brake-applying means carried by the other member;linkage means interconnecting said one member with the trailerbrake-applying means and responsive to relative movement between saidmembers to move in a brake-applying direction to actuate said trailerbrake-applying means to thereby actuate the trailer brakes; said othermember having a tubular section, said linkage means extending into saidtubular section and having a transversely extending abutment surfacewithin said tubular section; and locking means carried on said tubularsection, said locking means including a plunger having a bifurcated endpresenting a pair of legs, said legs straddling said linkage means, saidtubular section having a pair of openings receiving said legs and athird opening opposite said pair of openings receiving the opposite endof said plunger, and electrically actuated means adapted to be connectedto the vehicle back-up light circuit and being actuatable to shift saidplunger from a first position permitting said linkage means to moverelative to the tubular section to a second position in which theplunger cooperates with the abutment surface to inhibit movement of thelinkage means, thereby inhibiting operation of the trailerbrake-applying means to prevent actuation of the trailer brakes.